All regular doors have a lock hole predrilled thereon to mount with a lock therein for securing purpose, those lock holes are generally in two different sizes, one in 11/2 inches and the other in 21/8 inches. Though the lock also has tow different sizes, in many times, user found their lock is different in size to the door lock hole and have to run back and forth to get the right one which is very inconvenient.
In solving this problem, two patented arts, U.S. Pat. No. 5,335,525 and 5,540,070 are introduced into the market, U.S. Pat. No. 5,335,525 discloses a cylinder 22 of an adapter 16 is inserted into a groove 44 of a guard collar 18, and cylinder 24 into an opening 36 of the guard collar 18, whereas U.S. Pat. No. 5,540,070 connects an adapter 16 with a guard collar 12 and both are to solve the problem, however, these two are not the only way to solve the problem.